Cochran is below 50 percent and has slipped slightly from a Harper poll earlier this year.

The photo scandal is doing minimal damage to McDaniel among undecided voters.

Here's what Harper Polling said in their polling memo:

On the positive side of the ledger for Senator Thad Cochran, he maintains a lead just beyond the margin of error, his image with Republican voters is a net +16%, and 89% of voters have heard about the incident involving the photographing of the Senator's wife.

However, he is an incumbent under 50%, the photograph issue is not turning many voters against McDaniel who weren't already there, and he is under performing his favorable image rating (52%) by 7% on the ballot (45%).

The McDaniel campaign has not persuaded voters to dislike Cochran, but the argument for a fresh start is proving compelling. Compelling enough for voters who are in fact fond of the 6-term Senator to give serious consideration to bringing him home.

Chris McDaniel is bloody and bruised but still standing. His image rating is approaching 1-to-1 and the flow of the campaign messages in the race is giving voters a worsening opinion of McDaniel (37% favorable to 50% unfavorable). But it appears that the mission for McDaniel is merely to stay viable as an alternative to the long-time incumbent.

The race appears to be a referendum not on any perceived misdeeds of Thad Cochran but rather a more general desire for change in leadership in Mississippi.

In discussing the impact of the scandal over the course of the past few days, my stance has been this: It seems that the scandal has ignited McDaniel's base, which could really drive turnout in his favor.

McDaniel's base seems genuinely angry because they sincerely believe the Cochran camp sandbagged McDaniel by waiting three weeks to tell authorities. They also think Cochran using the scandal in TV ads against McDaniel — who has not been implicated — is as distasteful as someone sneaking and taking photos of Rose Cochran.

On the other hand, Cochran's base does not seem as excited about the race. Those who support Cochran think he's done a good job and believe he should keep doing it, and they've never had to worry about whether or not "Thad" would win. He always wins.

The Cochran base's lack of urgency and the ignited passions among McDaniel's base could make a difference Tuesday. This latest poll seems to support this theory. It also gives credence to Cochran's apparent do-no-harm strategy in these last weeks.

Keep Cochran away from the media, and he can't say or do anything that would hurt him, the theory goes. Of course, it's hard to build momentum that way. It's also hard to fire up your base, which is clearly a problem right now.

The survey polled 599 likely Republican primary voters from May 27-28. The geographic breakdown used is also representative of expected GOP turnout. The age breakdown skews a bit younger than average, which is likely accurate for this race. Only 58 percent of those polled are 66 or older. That may be slightly above where turnout ends up, but it likely won't be by much. Mississippi voter turnout still seems to skew older than the national average.